Anti-theft device having a cylinder lock

Abstract

A cylinder lock, particularly useful as a vehicle steering lock, of which the barrel is axially slidable between an outer, locked position and an inner position in which the barrel can be rotated by an appropriately coded key. Insertion of a key into the key passage of the barrel when the barrel is in the outer position is prevented by closure elements which are displaced by the leading end of the key, axial movement of the barrel from the outer to the inner position occurring during such displacement.

What is claimed is: 
     
       1. An anti-theft device comprising a lock body, a cylindrical barrel rotatably mounted in said body and including an axial passage for insertion of a key, locking means in said barrel engaging said body to prevent rotation of said barrel, said locking means being operable by insertion of a correctly coded key to free the barrel for rotation within the body, said barrel being axially slidable within said body between an outer, locked position and inner, operative position, closure means disposed at an entrance end of said axial passage and movable between a first position in which said means is effective to prevent insertion of a key into said passage in said outer position of said barrel and second position to allow insertion of the key into said passage in the inner, operative position of said barrel, and means biasing said closure means towards said first position, pressure applied to said closure means against the action of said biasing means by the leading end of the key, moving said barrel to said operative position and thereafter moving said closure means to said second position to allow insertion of said key into said passage, said barrel including an operating part rotatable therewith and cooperating with a bolt element to move that element between locking and releasing positions, said barrel being formed at that end thereof from which a key is inserted therein, with a T-sectioned slot, said closure means being guided for axial radial movement therein, a thrust ring disposed between opposed surfaces of said body and barrel and rotatable with said barrel, said ring including elements projecting into said slot and cooperating with said closure means, means biasing said barrel towards said outer position, and wherein a cap is rotatably mounted at that end of the barrel from which said key is inserted and between the thrust ring and a ring protecting said body, said cap being coupled to rotate with the barrel by lugs positively engaged in the T-shaped groove, said lugs being radially and axially contiguous with free ends of said parts of the thrust ring. 
     
     
       2. An anti-theft device comprising a lock body, a cylindrical barrel rotatably mounted in said body and including a axial passage for insertion of a key, locking means in said barrel engaging said body to prevent rotation of said barrel, said locking means being operable by insertion of a correctly coded key to free the barrel for rotation within the body, said barrel being axially slidable within said body between an outer, locked position and an inner, operative position, closure means disposed at an entrance end of said axial passage and movable between a first position in which said means is effective to prevent insertion of a key into said passage in said outer position of said barrel and a second position to allow insertion of the key into said passage in the inner, operative position of said barrel, and means biasing said closure means towards said first position and said barrel towards said outer position, pressure applied to said closure means against the action of said biasing means by the leading end of the key, moving said barrel to said operative position and threafter moving said closure means to said second position to allow insertion of said key into said passage, said barrel including an operating part rotatable therewith and cooperating with a bolt element to move that element between locking and releasing positions, said barrel being formed, at said entrance end, with a key-sectioned slot, said closure means being guided for axial and radial movement therein, a thrust ring disposed between opposed surfaces of said body and barrel and rotatable with said barrel, said ring having at least two arms projecting therefrom into said slot, said biasing means comprising a compression spring coacting between said ring and said barrel. 
     
     
       3. An anti-theft device as claimed in claim 2 wherein the barrel and the operating part cooperating with the bolt member are in one piece. 
     
     
       4. An anti-theft device as claimed in claim 3, wherein the operating part is an actuating drum having radial dimensions exceeding those of the barrel. 
     
     
       5. An anti-theft device as claimed in claim 2 wherein the compression spring coacting between the thrust ring and the barrel is a conical spring the larger diameter end of which bears against the thrust ring and the smaller diameter end of which bears against an annular collar of the barrel at that end thereof from which a key is inserted. 
     
     
       6. Apparatus as claimed in claim 2 wherein said closure means comprises a pair of cylindrical rollers and wherein said arms of said ring contact said rollers. 
     
     
       7. Apparatus as claimed in claim 6 wherein said biasing means comprises a conical spring disposed around said barrel and extending between said ring and an annular collar. 
     
     
       8. An anti-theft device as claimed in claim 2 wherein latch means are associated with said bolt and cooperate with said operating part to hold said bolt element in said releasing position until said barrel is returned to said outer locked position.